1. Field of the Invention
The invention relates to doors for aircraft or other vehicles which must be jettisoned from their frames both rapidly and easily to provide maximum opening for the quick exiting of occupants desiring to avoid or escape a hazard. It specifically pertains to the incorporation of a joint, associated with the door hinge mechanism, to free the door from its otherwise fixed but pivotable engagement with the frame.
2. Description of the Prior Art
Numerous means and devices have been utilized to provide emergency openings or complete release of doors and hatches for exiting of personnel. A number of these means include apparatus to pull or retract the hinge pins of the door or to rotate either the hinge pin or its support in order to align a necked-down portion of one member to a slot in the other member to allow separation of the two. An example of pin retraction is U.S. Pat. No. 2,369,148 to Langhorst, wherein pin-like journal members which normally function to provide pivot motions for mating hinge leaves may be retracted from contact to allow hinge separation. U.S. Pat. No. 2,346,977 to La Sha teaches a jettisonable aircraft door wherein cylindrical pivot pins are flattened locally to allow passage through similarly dimensioned slots in the hinge support when the pins are rotated into proper alignment. U.S. Pat. Nos. 3,032,834 to Carlson and 3,851,845 to Edwards teach similar rotation means. More recent U.S. Pat. No. 4,009,507 to Lascarrou provides mechanism for a cabinet door wherein the hinge pin is not retracted nor rotated, but the flattened cylindrical member rotation concept is followed by utilizing an additional member.
In the environment of the aircraft door to which this invention was initially made, removable or rotatable hinge pins were considered undesirable due to the usually long length of the pins, the resultant long stroke to retract them, and the high force required to be provided to move them due to their loaded condition. A further requirement dictated an aerodynamically smooth door and frame exterior, thus preempting use of a heretofore acceptable means of door jettison wherein a portion of the hinge support is rotated to allow freedom for the hinge pin. The apparatus of such means, including mating hinge members, are located on the aircraft exposed surface where they create undesirable drag.